Submission #3768882

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Source Code Expand

n, m = map(int,input().split())
f = [False for _ in range(n)]
c = [1 for _ in range(n)]
f[0] = True
for i in range(m):
  x, y = map(int,input().split())
  f[y - 1] = f[y - 1] or f[x - 1]
  c[y - 1] += 1
  c[x - 1] -= 1
  if c[x - 1] == 0:
    f[x - 1] = False
ans = 0
for i in range(n):
  if f[i] and c[i] > 0:
    ans += 1
print(ans)

Submission Info

Judge Result